Proper interpretation of the results of controlled clinical trials requires an assessment of not only the statistical significance of treatment differences but also of the clinical importance of such differences. Efforts to define criteria for important improvement in rheumatoid arthritis (RA) have thus far not considered the patient s perspective, even though patient s values represent the normative standard on which improvements should be judged. The specific aims of this project are to determine if group criteria for important improvement in arthritis activity measures can be defined by assessing the agreement among patients of judgments of important changes in arthritis activity, and to determine if preference measures are useful measures of the importance of clinical changes. Because the importance of changes can be meaningfully judged only for measures that are sensitive to change, the sensitivity to change of arthritis activity measures will also be assessed. This observational case series study will measure changes in 11 arthritis activity measures, changes in patent preference measures, and judgments of the importance of changes in arthritis activity over one to four months in 240 patients with active RA. Consensus among patients regarding the magnitude of change in each measure considered important would allow group criteria for important improvement to be defined that were based on patients' valuations. Lack of consensus among patients, and therefore inability to define meaningful group criteria for important improvement, may indicate that clinical trials should include endpoints that more directly reflect patients' valuations of health, such as preference measures. This study will therefore also examine the reliability, construct validity, and sensitivity to change of patient preference measures, and will determine if preference measures better reflect changes judged to be important than do changes in traditional arthritis activity measures. This study will allow investigators to plan studies with knowledge of clinically important differences in arthritis activity measures, and will help clinicians and patients to understand better the relative benefits of different treatments.